M.2 is a transmission interface of new standard specification established by PCI-SIG and SATA-IO associations. M.2, originally known as the NGFF (Next Generation Form Factor), is now called M.2. M.2 interface can support the standard specifications of SATA, USB and PCIe, has a variety of dimensions and the advantage of fast transmission speed, and can be applied to various kinds of expansion cards like the solid state disk (SSD), WIFI, Bluetooth and near field communication (NFC), etc.
Referring to FIG. 1(A) and FIG. 1(B), there are shown the three-dimensional views of the M.2 interface card inserted into the M.2 interface connection seat in prior arts. As shown in the figures, the M.2 interface connection seat 15 is disposed on a circuit board 10. The M.2 interface connection seat 15 is provided with a slot for inserting the M.2 interface card 11, and an opening direction of the slot is parallel to the surface of the circuit board 10. So the M.2 interface card 11 is inserted into the slot of the M.2 interface connection seat 15 in a horizontal direction.
The slot of the M.2 interface connection seat 15 is provided on at least one inner edge thereof with at least one metal spring. When the M.2 interface card 11 is inserted into the slot of the M.2 interface connection seat 15, the rear end of the M.2 interface card 11 may be upturned because the elasticity force of the metal spring, as shown in FIG. 1(A).
The rear end of the M.2 interface card 11 is provided with a notch 111, and the circuit board 10 is provided with a hole 101. When the M.2 interface card 11 is inserted into the M.2 interface connection seat 15, the notch 111 will be aligned with the hole 101 of the circuit board 10. A screw fixed member 17 can be used for fixing the M.2 interface card 11 on the circuit board 10 through the notch 111 and the hole 101 so as to avoid the upturned situation occurred on the rear end of the M.2 interface card 11, as shown in FIG. 1(B).
Currently, the M.2 interface card 11 is developed with various specifications like 22 mm (width)×30 mm (length), 22 mm×42 mm, 22 mm×60 mm, 22 mm×80 mm and 22 mm×110 mm. Besides, the hole 101 of the circuit board 10 is disposed on a fixed position, and therefore a fixed distance is exist between the M.2 interface connection seat 15 and the hole 101 of the circuit board 10. Accordingly, the length of the M.2 interface card must match with this fixed distance, or else the M.2 interface card 11 can not be fixed on the circuit board 10. Therefore, the selectivity of the specification of the M.2 interface card 11 will be limited when the M.2 interface card 11 is fixed by the way of locking.
Furthermore, the M.2 interface card 11 is fixed by adopting the way of locking, in which it requires a screwdriver to install the M.2 interface card 11 on the circuit board 10 or disassemble the M.2 interface card 11 from the circuit board 10, in such the way that there is a certain inconvenience in the operation.